Syntax:
ENCRYPT(str[,salt])

Encrypts str using the Unix crypt() system call and returns a binary
string. The salt argument must be a string with at least two characters
or the result will be NULL. If no salt argument is given, a random
value is used.

*Note*: The ENCRYPT() function is deprecated as of MySQL 5.7.6, will be
removed in a future MySQL release, and should no longer be used.
Consider using AES_ENCRYPT() instead.

URL: http://dev.mysql.com/doc/refman/5.7/en/encryption-functions.html

